Dressing fixture for grinding wheels



Feb. 7, 1939. .H A, D'NNECKER y 2,146,466

DRESSING FIXTURE FOR GRINDING WHEELS l H. A. lin-ANNE'CKER 2,146,466

DRESSING FIXTURE FOR GRINDING WHEELS Filed July 6, 1958 Feb. 7, 1939.

3 Sheets-Sheet 2 Feb. 7, 1939. H, A. DANNECKER 2,146,466

DRESSING FIXTURE FOR GRINDING WHEELS VFiled July 6, 1958 3 Sheets-Sheet3 Patented Feb. 7, 1939 UNITED STATES PATENT OFFICE DRESSING FIXTURE FORGRINDING WHEELS 1d claims.

My invention relates to a dressing fixture for grinding wheels andparticularly to a dressing fixture designed to provide the periphery ofa grinding Wheel with an elliptical cross section of 5 such curvaturethat when a form tool is ground therewith it will produce a truecircular cutting edge in the plane of the top or cutting face of thetool whereby, the tool so ground w'n'en utilized in an automatic machinewill operate upon the Work to embody in the latter a true sphere. y

It is my vobject to provide a dressing fixture for grinding wheels ofthe type and for the purpose specified which will avoid the'necessity ofextensive mathematical .computations and the use of templets in movingthe tool through different selected curvilinear paths and thus renderthe proper and successful operation of fixture Withinthe ability ofunskilled labor.

It is also the object of my invention to render the iixture easilyadjustable for the purpose of moving the diamond tool through the curveof the proper ellipse in accordance with the radius of the sphericalform desired tol be produced by the form tool to be ground.

'25 Furthermore, it is the object of' my inven- I will describe myinvention in the best form T40 known to me at present but it will beunderstood that the same is susceptible to change in form andproportions and to desirable additions with the exercise of lonlyordinary mechanical skill and without departing from the spirit thereof.

In the drawings chosen to illustrate my vin-v vention the scope whereofis set forth in the appended claims. v

Figure 1 is a' plan view of a dressing fixture for -grinding wheelsconstructed in accordance with my invention, the parts being in thepositions they would relatively occupy when it is desired to dress the-periphery of a grinding wheel transversely in a circular curve or arcor when it is desired to effect relative adjustment of the parts todetermine the radius of the spherical form desired to be produced by theform tool to be ground by the dressed grinding wheel;

Figure 2, a side elevation of Figure 1;

Figure 3, a section on the line 3--3 of Figure 2;

Figure 4, a section on the line 4 4 of Figure 1 with the parts of thefixture adjusted to a position effective to dress the periphery of agrinding wheel transversely with a predetermined elliptical curveessential to grinding a form tool of 10 a given rake angle so that saidtool will be provided With a circular cutting edge in the plane of itstop Aface to thereby render said tool capable of operating upon the workto produce a true spherical form; i l l5 Figures 5, 6 and'7 aresectionalviews on the line .5--5 of Figure 4 showing different positions of theparts in the operation of dressing the 'periphery of a grinding wheelwith an elliptical cross section. u

Figure 8,a detail view of the adjustable bearing arm;

Figure `9, a detail View of the rotary operating head of the fixturewhich has bearing in the arm shown in Figure 8; and

Figure 10, a detail view showing a grinding wheel dressed by my fixturein operative relation to a form tool being ground thereby to provide acircular cutting edge on the tool in the plane of its top face. 3;)

Referring to the drawings my improved fixture is shown comprising a baseI0 which is adapted to seat or rest upon a grinding machine car- Vriagewhereby the fixture may'be gradually elevated by the operator -towardthe grinding wheel being dressed all in amanner well known to thoseskilled in the art. On the base I0 I provide spaced lugs II and I2 andpivoted between these lugs on an axis parallel to the base I0 is a linkelement I3 and pivotally secured to the latter 40 is another linkelement I4 which has free end portions I5 and I6 rotatably engaged ontrunnions I1 and I8 respectively. .Fixed on the trunnions I1 and I8 is aU-shaped yoke or tool carrier I9 which has mounted in its arm ccnnect-45 ing portion a diamond tool 20 whose'cutting point 2| is located inthe axis of the trunnions I'I and I8. By this construction it will beapparent that the axis of the trunnions I'I and I 8 and of course thecutting point 2Iv are beneficially capable of 50 movement in unison inany direction in a plane at right angles to the axis of the pivotalyconnection between the link yelement I3 and base Ill. The trunnion II isextended outwardly from the end portion I5 of link element I4 andsplined on 55 this extension is a/sleeve 22 whose purpose Will presentlyappear.

Mounted on the base I ls a standard-23 and carried by this standard isan L-shaped member including arms 24 and 25, the former of which hasrotatable bearing in the standard 23 and is disposed parallel to theaxis of the trunnions I1 and I8, while the arm 25 is at right angles tosaid axis. It will thus be seen that the arms 24 and 25 of the L-shapedmember are angularly adjustable about the axis of the rotatable bearingof the arm 24 in standard 23, a screw 26 being provided for locking theL-shaped member in aU desired angular adjustment. I

Rotatably mounted in the arm 25 is a shaft 21 which has fixed on itsinner end a head 28 disposed radially of the axis of rotation of saidshaft. Outwardly of the arm 25 the shaft 21 has a reduced threadedportion 28' on which is screwed an operating knob 29. At its extremeouter end this shaft 21 is again reduced as at 30 and threaded on thisreduced portion is a locking or jam nut 3| which coacts with the knob 29to secure the latter against rotation on the shaft 21. The outer side ofthe head 28 is provided with a groove disposed radially of the axis ofrotation of the shaft 21. This groove contains a relatively wide outerportion 32 and a reduced inner portion 33 having converging sides 34.Seated in the portion 32 of said groove is an arm 35 of an L- shapedmember, the other arm of said member being indicated at 36. A clampingbolt'31 extends through the arm 35 and cooperates with a clamping nut 38located in the inner portion 33 of the groove to secure the memberformed by the arms 35 and 36 in selected adjustments on the head 28radially of the axis of rotation of shaft 21. Secured to the arm 36 is aU-shaped connection'including arms 39 disposed in embracing relation tothe sleeve 22 and pivotally connected respectivelyto said sleeve by conebearing members 40.

In Figures 5, 6 and '1 I show a grinding wheel 4| being dressed by myimproved fixture with the partsthereof in the relative positions shownin Figure 4 and wherein the fact is clearly'dis'closed that during theoperation of the fixture the diamond tool 20 is disposed normal to thecurvature of its path of movement at all times. This condition isbrought about by the fact that during oscillation of the head 28 thesleeve 22 will coact with the trunnion I1 to impart an oscillatingmovementl to the tool holder I9 relative to the linkage formed by theelements I3 and I4. These views also disclose clearly the changingrelative relation of the elements of the linkage and the tool carrierduring the operation of the flxtur through its cycle.

Figure 10 shows a form tool 42 being ground by a grinding wheel 4Idressed with its peripheral cross section elliptical. In this view thegrinding is substantially completed, the tool having ground thereinthrough its entire length a groove 43 of elliptical cross section.However, as the face of the cutting end of the tool is in a planeinclined to the tools axis to conform to its rake angle and for whichthe periphery of the Wheel was dressed it will be obvious that thecutting edge of the tool in said plane and within the limits of thegroove will be the arc of a true circle and that when the said tool isimposed upon work, said cutting edge will operate to impart to a portionof the work a form which will constitute at least a part of a truesphere.

The angular relation of the shaft. 21 to the plane in which the diamondtool 20 moves is determined by the rake angle of the form tool to beground by the dressed wheel. To render the adjustment of the shaft 21 tocorrect angular relation to said plane a simple matter I have calibratedthe arm 24 as at 44 in terms of various degrees of rake angles to beregistered with a positioning mark 45 on the standard 23. Thisadjustment of the member formed by the arms 24 and 25 and therefore thecorresponding adjustment of shaft 21 is effected by loosening theclamping bolt 26 and rotating the arm 24 on its axis to the right inFigures l and 2 until the desired calibration corresponding to the rakeangle of a desired form tool registers with the mark 45. The clampingbolt 26 is then tightened and the fixture is ready for a dressingoperation corelated to the angular adjustment of shaft 21 provided thefixture has also been adjusted with a view to the ultimate production ofa form tool beneficially capable of imparting tdwork a spherical shapehaving a predetermined radius. I leliect this lat ter adjustment whenthe parts of the fixture are in the positions shown in Figure 2. To thisend the bolt 31 is loosened and the member formed by the arms 35 and 36adjusted radially on the head 28 until the vertical distance betweenAthe axis of the trunnions I1 and I8 and the axis of the shaft 21 equalsthe desired radius. This adjustment can be easily accomplished bydeveloping a vertical measurement from the base I0 to the axis of shaft21 and another measurement fr'om the base I0 to the axis of I1 and I 8which is less than the rst measurement by an amount equal to the desiredradius. This second measurement will determine the radial adjustment ofthe member formed by the arms 35 and 36 with respect to the head 28. Thebolt 31 is then tightened and the angular adjustment of the shaft 21with respect to the plane in which the diamond tool moves is effected inthe manner previously referred to.

When the adjustments of the fixture have been completed the grindingwheel to be dressed is rotated and the carriage" of the grinding millgradually elevated to bring the diamond tool into Contact with theperiphery of the wheel. At the same time the workman gripping the knob29 oscillates the shaft 21. This oscillation of the shaft is transmittedto the trunnion I1 through the connections previously described andthereby the diamond tool is oscillated in a curved path which is aprojection on the plane in which the diamond tool moves of the circularpath of the head 28 and as the head 28 is disposed at an angle to saidplane the diamond tool will move in an elliptical path and dress theperiphery of the grinding wheel in accordance as the carriage of thegrinding machine is gradually elevated during the oscillation of thediamond tool.

1. In a dressing fixture for grinding wheels, a base, a linkage havingone end hinged to the base and its other end free, a tool holder carriedby the free end of the linkage for movement with the linkage, a toolcarried by the holder movable' with the latter and in a plane at rightangles to the axis of the hinge between the linkage and the base, amember mounted on the base for rotation on an axis at an angle to. saidplane, a connection between the member and tool holder whereby movementof said member in a circular path will operate through the holder toimpart movement to the tool in a curved path which is in which the toolmoves, and means to adjust saidmember to dispose its rotary axis indifferent 'selected angular. relations to said plane.

2. In a dressing fixture for grinding wheelsfa base, a tool'munted onthe basefor movement in a plane at' right angles tothe base, astandardmounted-on the base, a bearing arm parallel to said planevand mountedonsaid standard for angular adjustment about an axis also parallel tothe plane, a member having rotary bearing in said arm on an axis at anangleto said plane, and a. connection between the member and toolmounting whereby movement of saidV member in a circular path will impartmovement to the tool in a 'curved path which is theprojection of saidcircular path on the plane in which vthe tool'moves.' i y 3.*In adressing fixture for grinding wheels, a tool mounted on the base formovement in any direction in ariane at right angles to the base, astandard mounted on thebase, ajbearing arm parallel to said plane andmounted on said standl ard for angular adjustment aboutan axis alsoparallel to the plane, a shaft rotatably mounted arm radially thereof, asleeve splined on the tool mounting for sliding-movement? in a direction4. In a dressing fixture for grindingwheels, a

base, a linkage having one end hinged to the base and its 4other endfree, a tool holder carried by the free end of the linkage'for movementwith the linkage, a tool carried bythe holder for movement in a plane atright angles to the axis of the hinge between the linkage and the base,a sleeve splined on lthe tool holder for lsliding movement 'in a`direction at right angles to said plane, a member rotatably mounted onthe base with its rotary axis at an angle to thev plane lin which thetool moves, and a connection having one end iixed to the-member and itsother end pivoted to the sleeve.

5. In a dressing fixture forHeimann;wheat.l s-

bese, a U-shapedj member having laxially alined trunnions fixed to its aplural' axis of the trunnions. andmeanson the Y s. ma :mun a bue. aU-shnped tnmnions mounted mand fixedltoib lnectively. s

in said bearing arm and having xed thereto an linkage having one end tosaid base onv rotatablyensased on located in the common axis of thetrunnions, and means mounted on the base and connected with one of thetrunnions operable to move said U- shaped member and linkage to causethe common 'axis of the trunnions to move in a predetermined curvilinearpath, and to maintain the axis of the diamond tool at all times normalto the curvilinear path in which said diamond point moves.

7. In a dressing fixture for grinding wheels, a

base', a link`having one end pivoted to the base, a y

second link having one endpivoted to the other end of the first link onan axis parallel to the` pivoted axis between the first link andbase and'having its other end free, a tool holder carried by the-free end of thesecond link, a tool xedly' carried by the holder for movement therewith,a shaft mounted on the base for rotation on an axis at an angle to theplane in which the tool moves, and a crank connection between the shaftand tool holder operable upon rotation of the shaft to move the toolholder and'links to cause the cutting of the tool to travel apredetermined curvilinear path.

8. In' a dressing fixture for grinding wheels, a base, a link having oneend pivotedto the base, a second link having one end pivoted to theother end -of the `first link on an axis-parallel to the pivotal axisbetween the first link and base and having its` other end free, a toolholder carried by the free end of the second link, a tool fixedlycarried by the holder for movement therewith, a shaft mounted on thebase for rotation on an axis oblique the plane in which the tool moves,

and a crank connection between the shaft and tool'holder operable'uponrotation of the shaft to move the tool holder and links to cause thecutting point of the tool to'travel'ina predetermined curvilinear path.

9. In a dressing fixture for grinding wheels, a base, a linkage formedof a plurality of links pivotally connected together at adjacentterminals, said linkage having one end hinged to the base and its otherend free, a tool holder havingfixed pivotal connection with the free endof the linkage, a tool carried by the holder, an operator rotatablymounted on the base. and means between the operator and 'tool holderresponsive to the movement of the former to'both move and .solelycontrol the direction of movement of the

